有1000個硬幣和一個天平
其中有1個是假的
如何在以最少的次數找出來?
(假的硬幣較輕)
:notice:
:fight:
國中

回應

fuyaen

2006-06-18 17:24
等等..我懂了
你說的"可能六次"
是指說有的狀況下六次就能找出來了對吧
但是答案還是要以最多的為準
所以是七次

aa963854116

2006-06-20 17:59
嗯...這一類的題目我都不太會做...
該朝什麼方向想比較好?

孫文先

2006-06-20 19:18
先減少金幣數學，從2, 3, 4, ....開始探索，再設法歸納。

fuyaen

2006-06-20 21:17
基本上這種題目都差不多吧
要一次分成三堆
所以一次可以淘汰三分之二

訪客 (未驗證)

2006-08-15 21:14
1000/2=500...1次
500/2=250....2次
250/2=125...3次
125-1=124,124/2=62....4次(若相等,則扣掉的就是假的),62/2=31...5次,31-1=30,30/2=15...6次,15-1=14,14/2=7...7次7-1=6,6/2=3...8次3-1=2,2/2=1....9次...............9次

孫文先

2006-08-17 14:59
再給兩個天平問題

1. You have nine coins whose total weight is 9. Each individual coin has
weight 0, 1 or 2. Using a balance, what is the minimum number of weightings needed to sort the coins out by weight?

2. You have nine coins seven of which weigh the same. Of the other two coins, one is heavier and one is lighter than any of the seven. Using a balance, what is the minimum number of weightings needed to determine whether the total weight of these other two coins is greater than, equal to or less than the total weight of two of the other seven coins?

訪客 (未驗證)

2006-08-17 15:38
How can a coin weighs 0?

According to the statement of the question,
if 0, 1, 2 refer only to ranks, not quantity, the statement" that 9 coins whose total weight is 9" would be problematic, because ranks should not be added; Only quantities could be added with meaning.

The logic of the statement seems confusing. :-?

j7631103

2006-08-17 17:41
這類型的題目就像計算類的天平題目,不知輕重比較難,答案確定是7次

孫文先

2006-08-17 20:04

與其他種二幣比較，它的重量趨近於零，可忽略不計。